SCOTTSDALE, Ariz. (AP) - Phil Mickelson had an awful start in the FBR Open. He was 4 over after nine holes, 2 over after 18. Just making the cut seemed a reasonable goal.

What followed was a masterful, dominating performance that gave the Masters champion his first victory of the year, a five-stroke triumph that was the biggest winning margin in his impressive PGA Tour career.

"I thought it was going to be a short week, I'd have the weekend off," Mickelson said, "and the next thing you know I was able to turn things around."

That's an understatement. Mickelson was 19 under in the final 54 holes. The comeback began with an 11-under 60 in the second round, followed by a 65, and capped by a 67 on Sunday. As a finishing touch, he rolled in a 25-foot putt from the fringe on the 18th for a birdie, to the wild cheers of the huge crowd that had showered him with encouragement all week.

"I can't wait for next week," said Mickelson, looking forward to the AT&T Pebble Beach National Pro-Am. "I can't wait to get back on the golf course. I'm excited about hitting chips, or putts, or tee shots."

Mickelson said he's playing the best golf of his life, that his switch to new golf equipment has added distance to his drives. Those drives were a bit wild Sunday, when he hit one deep into the desert and another into a pond. But the 24-time PGA Tour winner offset those mistakes with brilliant comeback shots. He turned the desert mishap into a birdie, and salvaged a par out of the water.

Afterward, his daughters, 5-year-old Amanda and 3-year-old Sophia, rushed to hug their dad on the 18th green.

"Daddy, there's treats after," the youngest one said.

The victory in the $5.2 million event was worth $936,000. The best-attended tournament on the PGA Tour drew an estimated 517,000.

Mickelson accomplished his victory in an uncharacteristic way, tied for the lead after two rounds and up by four shots going into the final day.

"It was a fun week," he said, "because I drove the ball a lot longer than I think I have in years, and was able to have a lot of short irons, too."

With chants of "A-S-U!" and "Go Lefty!" from the crowd everywhere he went, Mickelson finished at 17-under 267 on the Tournament Players Club course.

Scott McCarron and Kevin Na, at 21 the youngest player on the PGA tour, tied for second at 272. McCarron shot his second consecutive 65, and Na had a 69. Na played in the final group with Mickelson and faltered before rallying with birdies on the 14th and 17th for his best finish in his two years on the tour.

Steve Flesch, Tim Herron and David Toms finished at 273. Toms would have finished in second place but double-bogeyed the 18th.

Mickelson, a three-time NCAA champion at Arizona State who lived in Scottsdale until December 2001, won the FBR - formerly the Phoenix Open - for the second time. He was just 25 when he won in a playoff with Justin Leonard in 1996.

The par-5, 13th might have been the clincher for Mickelson. His drive sailed off to the right, into desert terrain amid rocks, small trees and cactus. But the ball landed in a spot where there was an opening, and Mickelson smashed his 5-iron shot some 230 yards over a small tree and just in front of the green. He barely missed from there, then tapped in for a birdie. Na, meanwhile, three-putted for a bogey.

"I was thinking, 'This is my chance. I can make a three-shot swing here if I make eagle and he makes bogey,"' Na said. "It was the other way around."

Then on the par-5 15th, Mickelson drove into the water, but came back to save par.

"I certainly got up and down a lot," he said. "It's nice to have a short game to fall back on if I'm not hitting it the best," he said. "I probably didn't strike it nearly as well today as I did the last couple of days, but the score was OK. All I wanted to do was get the 'W' and I did that."

Na, born in South Korea, moved with his family to the United States at age 8. He turned professional at 17, before his senior year in high school, and earned a spot on the PGA Tour in the 2003 qualifying tournament. He knew the value gained in playing the final two rounds in the same group as Mickelson.